North American Birds



Thede Tobish, Regional Report Compiler

This dynamic region of dramatic weather and geographic extremes occupies the continent’s northwest corner, and it flirts with the Palearctic via the Aleutian archipelago and the Bering Strait. Spanning more than 27 degrees of latitude and 62 degrees of longitude, Alaska is the largest U.S. state. It comprises more than 20% of the land mass of the Lower 48 states and is bounded by 33,904 miles of shoreline.

The region includes diverse bioregions, ranging from coastal temperate rainforests to alpine and high Arctic coastal tundras. Alaska stands at the forefront of global climate change. Brina Kessel delineated 29 avian habitats in the region, and many of these are rapidly changing, including the advance of brush thickets into tundra biomes. Climate-change-caused alterations to migration timing and breeding distribution are already documented.

Avian status, distribution, and diversity are directly influenced by physical and geographic factors including climate, marine currents, prevailing weather, pack ice patterns, geology, historic ice ages, and proximity to Old World avian populations. A large percentage of the Alaska checklist reflects Palearctic affinities, and some species contained therein evolved in Beringia during prior ice ages. These include the unique Aethia auklets, which are still largely restricted to Beringia. Other iconic species with isolated breeding ranges here include Emperor Goose and Bristle-thighed Curlew. The semi-permanent low-pressure block known as the Aleutian Low has historically drawn storms from the west-central Pacific across the Aleutian Islands and the southern Bering Sea before steering these systems into the Pacific Northwest. This weather generator plays a major role in the presence and regularity of dozens of species of Old World migrants in the Aleutians and Bering Sea outposts.

Many famous early ornithologists with research and publications from the Pacific states made a mark in Alaska. The Alaska checklist and early taxonomic delineations took definition from works by Grinnell, Swarth, Bailey, Willett, and Gabrielson. Early Alaska specialists such as Murie were followed by Kessel and Gibson, who made the University of Alaska Museum the foremost specimen repository of Alaskan birds. New species with varied affinities continue to be added to the Alaska checklist.

The ABA gratefully acknowledges the contributions of Alaska Regional Report Compiler Thede Tobish to promoting knowledge and understanding about the birdlife of the continent.



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